According to WebMD, lip stain is a liquid makeup product designed to give long-lasting color by staining the lips. It is generally applied by brush or pen. Lip stain is ideal for a person who wants all-day color without having to reapply a lip product.
According to WebMD, the color from lip stain may settle into cracked or dry lips in an unflattering way. The Make-up Studio recommends using lip stain by itself to enhance a person's natural lip color. It also suggests wearing a layer of lip stain under lipstick or lip gloss to provide longer-lasting, more vibrant color.